Priapism associated with the use of levomepromazine. Case report

Abstract

Introduction: Priapism is a prolonged, painful erection lasting over four hours, constituting a urologic emergency. Among pharmacological causes, antipsychotics are responsible for nearly half of reported cases, mainly due to α1-adrenergic receptor blockade.
Objective: To describe a case of priapism associated with the use of levomepromazine, an antipsychotic that rarely may cause this adverse effect; integrating an analysis of the possible pharmacological mechanisms involved and highlighting the importance of an effective doctor–patient therapeutic relationship for the early detection of serious adverse effects.

Case presentation: A 30-year-old male patient with a prior diagnosis of mixed anxiety and depression presented with a painful, sustained erection lasting more than 15 hours after self-administering levomepromazine for insomnia. He was initially evaluated by the urology service, which performed corporal cavernosa drainage, revealing fibrosis of the left corpus cavernosum, possibly secondary to previous episodes of priapism. During follow-up, the patient experienced recurrence of the condition, prompting cavernous blood gas analysis, the urology team interpreted these findings as consistent with venous blood, supporting the diagnosis of low-flow priapism. As part of a multidisciplinary management approach, the psychiatry service discontinued levomepromazine and initiated treatment with gabapentin and clonazepam, with favorable clinical evolution.

Discussion: Levomepromazine’s high α1-adrenergic affinity can precipitate priapism, particularly in self-medicating patients with prior episodes. Early recognition, patient education, and a trusting therapeutic alliance are crucial to prevent complications.